Big Cormorant is regarded as an excellent natural prairie Walleye lake. At 3,657 acres, it is the second largest lake in Becker County. Its relatively close proximity to the Fargo-Moorhead area results in heavy angling pressure and shoreline development.
High water levels during the late 1990's resulted not only in changes to the shoreline and low-lying homes and cabins, but also in changes to the fish community. The recently high water levels opened up additional Northern Pike spawning habitat and the lake's pike population is still responding. The catch rate of pike has been well above normal for this lake since 2002 with a combined average over five surveys of 7.8 pike per net. The high water effects on the pike population is illustrated in the fact that in seven surveys prior to 2002, the average catch rate of Northern Pike was just 1.8 per set. Increases in numbers of small pike often result in decreases in Yellow Perch, the primary forage fish for Walleye and Northern Pike in most lakes. This is what appears to be occurring in Big Cormorant since Yellow Perch catches have remained lower than normal since 2002.
Fortunately, the Walleye population does not appear to have been adversely affected by the abnormally high Northern Pike numbers. The 2014 Walleye catch rate was lower than the lake's historical average, but still well above the normal range for similar lakes. Sampled Walleyes averaged 15.4 inches in length and 1.5 pounds in weight in 2014. In addition to the periodic, mid-summer test netting, the DNR began annual, fall electrofishing for young-of-the-year Walleyes in Big Cormorant in 2000. These studies have been good predictors of year class strengths for the future fishery. Cormorant Lake is an excellent natural Walleye lake with a strong 2011 year class poised to enter the current fishery. The 2005 and 2009 year classes also continue to make up significant portions of the Walleye sample in 2014.
Smallmouth Bass are another target species present in good numbers. Smallmouth Bass and Bluegill catches were higher than the lake's historical averages in 2014 and sizes are good for both species. Smallmouth Bass over 19 inches and Bluegills over nine inches were sampled during test netting and spring electrofishing. Black Crappies and Largemouth Bass can also be found in moderate numbers.
- Zebra Mussel
Recreational activities such as recreational boating, angling, waterfowl hunting, and diving may spread aquatic invasive species. Some aquatic invasive species can attach to boats, while others can become tangled on propellers, anchor lines, or boat trailers. Many species can survive in bilge water, ballast tanks, and motors or may hide in dirt or sand that clings to nets, buckets, anchors, and waders. Fortunately, completing simple steps can prevent the transport of aquatic invasive species.